Feeding Management For Optimum Growth, Reproduction And First Lactation Performance In Sahiwal Heifers

Material type: BookPublisher: 2010Subject(s): Department of Livestock Production | Phd. thesisDDC classification: 1230,T Dissertation note: Sahiwal is well known dairy cattle breed in the tropical and subtropical regions of world for its excellent heat and tick resistance. The value of adequate nutrition and management of replacement heifers is mostly overlooked and production losses linked with slow growth rate are not entirely realized. Efficient utilization of nutrients like energy during pre pubertal and gestation periods is needful for melioration. The study included two experiments. The aim in first experiment was to investigate the effect of varying dietary energy levels on pre pubertal growth and age at puberty in Sahiwal heifers. Twenty Sahiwal heifers (Age = 12 ± 2 month and avg. wt = 125 kg) were assigned to four dietary treatments having five animals on each treatment. Isonitrogenous (CP=13.7%) diets having varying energy levels, viz; A=100% (Control), B=88%, C=112% and D=124% of NRC recommended level for small breed non bred heifers were fed to the respective groups until onset of puberty.
Dry matter and protein intakes were not influenced by varying dietary energy levels during pre pubertal period. However, metabolizable energy (ME) 124% of NRC recommendation enhanced average daily gain (ADG) up to 571±15 g/d which was higher than all other dietary energy levels, whereas it was similar between ME 100% and ME 112% (442±11 and 450±05 g/d, respectively) but lower in ME 88% (397±07 g/d). The improvement in ADG of heifers fed ME 124% of NRC might be attributed to availability of excess energy nutrient for heifers to fulfill not only maintenance requirements but also to grow and develop body reserves. Provision of extra dietary energy improved efficiency of diets which might be attributed to availability of surplus dietary energy enabling heifers to convert feed into live body mass more efficiently. The 13 to 18 months of age was found optimum time period to have significantly highest ADG in Sahiwal heifers. This might be attributed to propitious physiological conditions under which heifers grow at faster rate.
The optimum increase in body structures (Body length, height and heart girth) was achieved in ME 124% of NRC recommendations. The phase from 13 to 18 months of age was found optimum possessing significantly highest values of increase in body length and heart girth, whereas phase from 19 months to age at puberty was optimum to achieve significantly highest body height. The optimum increase in heart girth during first two phases (13 to 19 months of age) might be attributed to relatively faster muscle growth in body than bone growth. The digestibility percentages of nutrients (DM, CP, NDF and ADF) were not influenced by different dietary energy levels. No influence of dietary energy levels on digestibility of nutrients in the present study might be attributed to best adaptability of Sahiwal heifers to utilize diets even with low energy under local environment.
Similarly, age at puberty was also not affected by dietary treatments and overall average was 833 ± 10 days. The optimum performance in terms of age at puberty at lower dietary energy level might be attributed to lesser energy requirements of Sahiwal under tropical and subtropical environment condition as elaborated by NRC (2000) that maintenance energy requirements of Bos indicus breeds including Sahiwal are about 10% lower. The similar pattern of influence was observed in serum progesterone concentration. The average of progesterone detected during a month before puberty was 0.44±0.005 ng/mL and during a month after onset of puberty was 1.48 ± 0.03 ng/mL serums. The similar rogesterone concentration among dietary treatments might be attributed to similar age at puberty in Sahiwal heifers.
It is concluded from results of first experiment that higher dietary energy level (ME 124% of NRC) enhanced growth parameters and feed efficiency but reproductive performance of Sahiwal heifers in terms of age at puberty was optimum even at lower dietary energy level (ME 88% of NRC recommended level) under local environment conditions of Pakistan.
The aim in second experiment was to study the effect of feeding varying dietary energy levels during last trimester of pregnancy on 1st lactation performance in Sahiwal heifers. Five to six months pregnant Sahiwal heifers (n=16) were assigned four dietary treatments having four heifers on each treatment. Iso-nitrogenous (CP=14.1%) diets having varying energy levels, viz; A=100% (Control), B=88%, C=112% and D=124% percent of NRC recommended level for pregnant heifers were fed to the respective groups until calving. After calving, all heifers were fed a similar diet having CP (16.2%) and ME (1.72 Mcal/kg).
Dry matter and CP intakes were similar across the dietary treatments. Pre calving ADG was not different among heifers fed ME 112 and ME 124% (486 ± 13 and 497 ± 05 g/d, respectively) but higher than other diets, whereas it was also higher (444 ± 07 g/d) in ME 100% than 397 ± 08 g/day in ME 88% of NRC recommendation. Feed efficiency was similar between ME 124 and ME 112% but higher than other diets, whereas ME 100% was also more efficient than ME 88% of NRC recommendation. The higher feed efficiency in higher dietary energy levels might be attributed to availability of surplus dietary energy enabling heifers to convert feed into live body mass more efficiently. Better body score through higher pre calving dietary energy level might be attributed to availability of energy for animal in surplus to its requirements of maintenance and pregnancy. Higher level of energy at this stage enabled pregnant heifers to develop extra body reserves needed in early lactation period to fulfill high demand of lactogenesis. The similar birth weight of newly born calves might be attributed to the factor that needs of conceptus (growth of fetus, fetal membranes, uterus and mammary glands) are accorded high priority by the homeorhetic controls it transmits to the dam.
Extra energy levels beyond NRC recommendation during prepartum period were not advantageous to increase milk yield in 1st calf heifers. The performance of 1st calf heifers in terms of milk yield was only optimum through pre calving feeding according to NRC recommendations. The lesser milk yield in diets having higher energy levels than recommended by NRC might be attributed to more availability of mammary fat pad which may limit further parenchymal tissue development and consequently decrease milk yield during subsequent lactation. However, milk fat percentage increased as pre calving dietary energy level was increased, whereas milk protein, lactose and SNF percent among animals fed different experimental diets did not differ. It is concluded from results of second experiment that the optimal performance of pregnant Sahiwal heifers was achieved through provision of pre calving extra dietary energy (ME 112%) beyond the NRC recommendation but first lactation yield was found optimum in heifers fed diet having energy level as per recommendations of NRC.

Sahiwal is well known dairy cattle breed in the tropical and subtropical regions of world for its excellent heat and tick resistance. The value of adequate nutrition and management of replacement heifers is mostly overlooked and production losses linked with slow growth rate are not entirely realized. Efficient utilization of nutrients like energy during pre pubertal and gestation periods is needful for melioration. The study included two experiments. The aim in first experiment was to investigate the effect of varying dietary energy levels on pre pubertal growth and age at puberty in Sahiwal heifers. Twenty Sahiwal heifers (Age = 12 ± 2 month and avg. wt = 125 kg) were assigned to four dietary treatments having five animals on each treatment. Isonitrogenous (CP=13.7%) diets having varying energy levels, viz; A=100% (Control), B=88%, C=112% and D=124% of NRC recommended level for small breed non bred heifers were fed to the respective groups until onset of puberty.

Dry matter and protein intakes were not influenced by varying dietary energy levels during pre pubertal period. However, metabolizable energy (ME) 124% of NRC recommendation enhanced average daily gain (ADG) up to 571±15 g/d which was higher than all other dietary energy levels, whereas it was similar between ME 100% and ME 112% (442±11 and 450±05 g/d, respectively) but lower in ME 88% (397±07 g/d). The improvement in ADG of heifers fed ME 124% of NRC might be attributed to availability of excess energy nutrient for heifers to fulfill not only maintenance requirements but also to grow and develop body reserves. Provision of extra dietary energy improved efficiency of diets which might be attributed to availability of surplus dietary energy enabling heifers to convert feed into live body mass more efficiently. The 13 to 18 months of age was found optimum time period to have significantly highest ADG in Sahiwal heifers. This might be attributed to propitious physiological conditions under which heifers grow at faster rate.

The optimum increase in body structures (Body length, height and heart girth) was achieved in ME 124% of NRC recommendations. The phase from 13 to 18 months of age was found optimum possessing significantly highest values of increase in body length and heart girth, whereas phase from 19 months to age at puberty was optimum to achieve significantly highest body height. The optimum increase in heart girth during first two phases (13 to 19 months of age) might be attributed to relatively faster muscle growth in body than bone growth. The digestibility percentages of nutrients (DM, CP, NDF and ADF) were not influenced by different dietary energy levels. No influence of dietary energy levels on digestibility of nutrients in the present study might be attributed to best adaptability of Sahiwal heifers to utilize diets even with low energy under local environment.

Similarly, age at puberty was also not affected by dietary treatments and overall average was 833 ± 10 days. The optimum performance in terms of age at puberty at lower dietary energy level might be attributed to lesser energy requirements of Sahiwal under tropical and subtropical environment condition as elaborated by NRC (2000) that maintenance energy requirements of Bos indicus breeds including Sahiwal are about 10% lower. The similar pattern of influence was observed in serum progesterone concentration. The average of progesterone detected during a month before puberty was 0.44±0.005 ng/mL and during a month after onset of puberty was 1.48 ± 0.03 ng/mL serums. The similar rogesterone concentration among dietary treatments might be attributed to similar age at puberty in Sahiwal heifers.

It is concluded from results of first experiment that higher dietary energy level (ME 124% of NRC) enhanced growth parameters and feed efficiency but reproductive performance of Sahiwal heifers in terms of age at puberty was optimum even at lower dietary energy level (ME 88% of NRC recommended level) under local environment conditions of Pakistan.

The aim in second experiment was to study the effect of feeding varying dietary energy levels during last trimester of pregnancy on 1st lactation performance in Sahiwal heifers. Five to six months pregnant Sahiwal heifers (n=16) were assigned four dietary treatments having four heifers on each treatment. Iso-nitrogenous (CP=14.1%) diets having varying energy levels, viz; A=100% (Control), B=88%, C=112% and D=124% percent of NRC recommended level for pregnant heifers were fed to the respective groups until calving. After calving, all heifers were fed a similar diet having CP (16.2%) and ME (1.72 Mcal/kg).

Dry matter and CP intakes were similar across the dietary treatments. Pre calving ADG was not different among heifers fed ME 112 and ME 124% (486 ± 13 and 497 ± 05 g/d, respectively) but higher than other diets, whereas it was also higher (444 ± 07 g/d) in ME 100% than 397 ± 08 g/day in ME 88% of NRC recommendation. Feed efficiency was similar between ME 124 and ME 112% but higher than other diets, whereas ME 100% was also more efficient than ME 88% of NRC recommendation. The higher feed efficiency in higher dietary energy levels might be attributed to availability of surplus dietary energy enabling heifers to convert feed into live body mass more efficiently. Better body score through higher pre calving dietary energy level might be attributed to availability of energy for animal in surplus to its requirements of maintenance and pregnancy. Higher level of energy at this stage enabled pregnant heifers to develop extra body reserves needed in early lactation period to fulfill high demand of lactogenesis. The similar birth weight of newly born calves might be attributed to the factor that needs of conceptus (growth of fetus, fetal membranes, uterus and mammary glands) are accorded high priority by the homeorhetic controls it transmits to the dam.

Extra energy levels beyond NRC recommendation during prepartum period were not advantageous to increase milk yield in 1st calf heifers. The performance of 1st calf heifers in terms of milk yield was only optimum through pre calving feeding according to NRC recommendations. The lesser milk yield in diets having higher energy levels than recommended by NRC might be attributed to more availability of mammary fat pad which may limit further parenchymal tissue development and consequently decrease milk yield during subsequent lactation. However, milk fat percentage increased as pre calving dietary energy level was increased, whereas milk protein, lactose and SNF percent among animals fed different experimental diets did not differ. It is concluded from results of second experiment that the optimal performance of pregnant Sahiwal heifers was achieved through provision of pre calving extra dietary energy (ME 112%) beyond the NRC recommendation but first lactation yield was found optimum in heifers fed diet having energy level as per recommendations of NRC.

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